In the metal processing industry, strips of metal are passed through coil to coil rolling lines to enhance the thickness tolerence and the flatness of the metal.
Small diameter work rolls are employed on the rolling machines to reduce thickness and large diameter are used for flatness corrections.
It is necessary for the strip to be subjected to tension less than the yield point in order to keep the point of slip as far ahead of the roll centerline as possible.
The coils of metal to be rolled are usually slit to a specified width prior to rolling but in some cases the slitting may be performed after rolling.
This slitting operation is carried out on a coil to coil type line.
When coils of metal are slit, a problem occurs due to the crown or thickness variation in the mother coil. As slit strips of different thicknesses wind up on a recoiler, the individual coils wind up at different diameters, which causes a slack or loose condition on some of the strips.
Different methods have been devised to overcome this slack loop problem ranging from the insertion of a paper filler material in the loose strips to accumulation pits and tensioning devices between the slitter and recoiler. One method discussed in U.S. Pat. No. 4,614,101 inserts a levelling device between a slitter and recoiler.
These teachings and operations are well known by those skilled in this art.